JPH11306702A - Magnetic medium inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the amplitude of residual vibration after the positioning so as to reduce a time period required as a setting time. SOLUTION: A magnetic medium inspection apparatus has magnetic heads 3A, 3B for performing writing and readout of data for a magnetic medium, supporting arm means 4A, 4B for supporting the magnetic heads 3A, 3B, and carriage means 9 for holding the supporting arm means 4A, 4B and performing the positioning between the magnetic heads 3A, 3B and the magnetic medium. In this apparatus, actuator means 6A, 6B are further provided for vibrating the supporting arm means 4A, 4B in directions canceling vibrations of the magnetic heads 3A, 3B generated in response to the positioning operation of the carriage means 9. The carriage means 9 generates characteristic vibration due to its inertial mass at the time of the positioning operation. However, in this apparatus, the actuator means 6A, 6B vibrate the supporting arm means 4A, 4B in the directions canceling this characteristic vibration. Thus, residual vibration is reduced when the positioning is stopped and a time period required for stopping the positioning is significantly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic media inspection apparatus suitable for a certification inspection for inspecting defects and magnetic properties of a magnetic film of a magnetic medium such as a magnetic disk, and more particularly to a magnetic head used for inspection. The present invention relates to a magnetic media inspection device with improved positioning.

[0002]

2. Description of the Related Art In recent years, a hard disk device has become standard equipment as an information storage medium of a personal computer, and its capacity is about several gigabytes. Also, in a notebook personal computer, it is desired that a high-density hard disk device can be built in a small volume. In order to increase the storage density of a hard disk drive, the track pitch for recording and reproduction must be reduced.

In the case of a certification inspection for inspecting a magnetic film for defects and magnetic properties of a magnetic disk having a small track pitch, the relative displacement between the inspection magnetic head and the track is reduced to about 5% or less of the track pitch. Unless it is suppressed, accurate inspection cannot be performed. For example, when the track pitch is 8 μm, the allowable relative displacement between the magnetic head and the track must be about 0.2 μm or less in terms of deflection.

[0004]

Conventionally, a stepping motor is generally used in a carriage structure for positioning a magnetic head, so that there is a problem that a step-like residual vibration is likely to occur during positioning. For example, when the track pitch is 8 μm, the movement time required for the movement is about 4 msec, and the amplitude of the residual vibration is about 0.2 μm.
The settling time until convergence to about m is about 4 msec, and the total positioning time is about 8 msec. Therefore, in order to perform high-speed positioning, use a stepping motor having a small basic step amount and a high rigidity, or reducing the lead of the feed screw, so that the rigidity of the carriage structure is secured. Or a motor with a high natural vibration and a large torque to inertia ratio,
This problem has been dealt with using a dedicated driver with small torque unevenness for each excitation phase.

However, there is a limit to such measures, and in recent years, track pitches have become smaller and smaller in order to further increase the recording density. It is important to keep vibrations as low as possible. Further, as the track pitch becomes smaller, the number of tracks on the surface of the magnetic disk further increases, so that it takes a lot of inspection time to inspect all the tracks.
Also in this case, it is an important issue for performing the inspection at high speed to enable the residual vibration after the positioning to be performed in a short time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and it is intended to shorten the positioning time by suppressing the fluctuation width of the residual vibration after the positioning and shortening the time required for the settling time. It is an object of the present invention to provide a magnetic media inspection apparatus capable of greatly shortening an inspection time.

[0007]

According to the present invention, there is provided a magnetic medium inspection apparatus for writing and reading data to and from a magnetic medium, and supports the magnetic head. Support arm means;
In a magnetic media inspection apparatus, comprising: a carriage unit that holds the support arm unit and performs positioning between the magnetic head and the magnetic medium, the vibration of the magnetic head that oscillates in accordance with the positioning operation of the carriage unit. An actuator means for vibrating the support arm means in the direction of canceling is provided. The carriage means generates a natural vibration due to its own inertial mass during the positioning operation. Since this natural vibration appears as residual vibration when the positioning is stopped, the magnetic head cannot be easily stopped at the target position. Therefore, in the present invention, by vibrating the support arm means in a direction to cancel the natural vibration, the residual vibration at the time of the positioning stop can be reduced, and the positioning stop time can be greatly reduced.

[0008] The magnetic media inspection apparatus according to the invention as claimed in claim 2 of the present application is an acceleration sensor for detecting acceleration when the carriage means moves, and the actuator means in accordance with an acceleration signal from the acceleration sensor. And control means for setting the vibration of.
When controlling the vibration of the actuator means, the positioning operation is performed in advance, the vibration waveform for canceling the residual vibration at that time is stored as a parameter, and the residual vibration is canceled based on the vibration waveform at the time of the positioning operation. Alternatively, as in the present invention, an acceleration sensor may be provided on the carriage means, and the vibration of the actuator means may be controlled in accordance with the acceleration signal from the acceleration sensor.

The magnetic media inspection apparatus according to the invention as claimed in claim 3 of the present invention is such that the actuator is constituted by a piezo-type actuator, and a bias in the extension direction is applied to the actuator in advance. It is. Piezo actuators are susceptible to shear forces and will break if not used in a compressed environment.
A bias is applied in the extension direction, and the expansion and contraction operation is performed based on the bias.

A magnetic media inspection apparatus according to a fourth aspect of the present invention is provided with a filter means for removing a high-frequency noise component from the acceleration signal between the acceleration sensor and the control means. It is. Since the acceleration and the position have a differential relationship, the high frequency noise component superimposed on the acceleration signal is removed by this filter means.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration according to an embodiment of a magnetic media inspection apparatus of the present invention. Hereinafter, a magnetic disk will be described as an example of a magnetic medium in this specification. The disk rotating mechanism 1 holds the magnetic disk 2 and rotates the magnetic disk 2 at a predetermined number of rotations, and includes a spindle motor and the like. The magnetic head 3A contacts the upper surface side of the magnetic disk 2,
The magnetic head 3B is provided so as to be in contact with the lower surface of the magnetic disk 2.

Each of the magnetic heads 3A and 3B has both a write inductive head and a read MR head. The magnetic heads 3A and 3B are provided on one end side of the support arms 4A and 4B, respectively. The other ends of the support arms 4A, 4B are connected to the piezo actuators 6A, 6 via L-shaped slide guides 5A, 5B.
B is attached to one end side. The other ends of the piezo actuators 6A, 5B are L-shaped fixing members 7A,
It is fixed to the support rods 8A and 8B by 7B. Accordingly, when the piezo actuators 6A, 6B expand and contract, the L-shaped slide guides 5A, 5B move accordingly, so that the support arms 4A, 4B and the magnetic heads 3A, 3B move in the normal direction of the magnetic disk 2 together. Become.

The support rods 8A, 8B are connected to the magnetic heads 3A, 3B.
It is attached to a carriage mechanism 9 for positioning B. The carriage mechanism 9 moves the support rods 8A and 8B by a stepping motor (not shown) to control the magnetic heads 3A and 3B to stop positioning at predetermined track positions. The carriage mechanism 9 is provided with an acceleration sensor 10. The acceleration sensor 10 detects an acceleration component corresponding to the movement operation of the carriage mechanism 9, and supplies a detection signal to the MPU 11 via the filter 1A. The filter 1A shapes the output waveform of the acceleration sensor 10 and removes high-frequency noise.

The MPU 11 is a microcomputer system for controlling the operation of the whole magnetic media inspection apparatus.
It is configured with a program ROM and a working RAM (not shown). The memory 12 is a memory medium for storing inspection results, and includes a large-capacity memory such as a hard disk. The printer 13 prints out the inspection result. The write control circuit 14 sends test data corresponding to a write command from the MPU 11 to the magnetic head 3.
A and 3B are output to the inductive head, and predetermined inspection data is written to the magnetic disk 2. The read control circuit 15 supplies the data read from the MR heads of the magnetic heads 3A and 3B to the MPU 11.

The motor control circuit 16 outputs a control signal of a pulse motor mounted on the carriage mechanism 9 to a motor drive circuit 17. The motor driving circuit 17 outputs a driving pulse to the pulse motor. The applied voltage control circuit 18 controls a voltage waveform applied to the piezo actuators 6A and 6B, and outputs a control signal to the applied voltage generation circuit 19. The control signal output from the applied voltage control circuit 18 has a vibration waveform that cancels residual vibration generated during the positioning operation of the carriage mechanism 9 as described later. The applied voltage generation circuit 19 includes the applied voltage control circuit 1
8 supplies an applied voltage according to the control signal from the piezo actuators 6A and 6B. Piezo actuator 6
A and 6B are constantly supplied with a constant bias voltage, and when a positive voltage is applied to this bias voltage, the magnetic disks A and 6B extend so as to approach the center of the magnetic disk 2,
Conversely, when a negative voltage is applied to the bias voltage,
The magnetic disk 2 operates so as to be reduced away from the center. Normally, the piezo actuator is weak under shear force and breaks if not used in a compression environment, so it is usually used in a compression environment. An operation area is secured.

Next, referring to the waveform diagrams of FIGS. 2 and 3, FIG.
The operation of the magnetic media inspection apparatus will be described. FIG. 2 (A)
FIG. 7 is a diagram showing an example of a position command waveform when the carriage mechanism 9 is moved to a target position and positioning is stopped. FIG.
(B) is a diagram showing an actual position waveform actually moved by the carriage mechanism 9 based on the position command waveform. The position command waveform stops the carriage mechanism 9 at the target position after a predetermined time. However, in practice, a natural vibration occurs due to the inertial mass of the motor constituting the carriage mechanism 9 and the carriage itself, which appears as residual vibration as shown in FIG. 2B and does not easily stop at the target position.

FIG. 2C is a diagram showing a waveform (acceleration waveform) output from the acceleration sensor 10 provided in the carriage mechanism 9 when the carriage mechanism 9 moves as shown in FIG. 2B. . The output waveform of the acceleration sensor 10 corresponds to a waveform obtained by differentiating the position waveform of the carriage mechanism 9 shown in FIG. 2B twice, but actually causes some errors due to waveform distortion and phase shift. FIG.
2A is an error indicating a position error between the target position and the actual position of the carriage obtained by subtracting the actual position waveform of the carriage mechanism 9 of FIG. 2B from the target command waveform of FIG. It is a waveform. The acceleration waveform of FIG. 2 (C) and the position error waveform of FIG. 3 (A) have a 180 ° out of phase relationship. That is, when the acceleration waveform has a positive value, the position error has a negative value, and when the acceleration waveform has a negative value, the position error has a positive value.

By supplying an applied voltage based on the acceleration waveform shown in FIG. 2C to the piezo actuators 6A and 6B, the piezo actuators 6A and 6B are turned on as shown in FIG.
The expansion / contraction operation based on the expansion / contraction waveform as described above is performed. That is, the expansion and contraction operations of the piezo actuators 6A and 6B function to cancel the position error in FIG. As a result, the positions of the support rods 8A and 8B are set as shown in FIG.
As shown in FIG. 2C, a waveform close to the target position waveform in FIG. As is clear from the waveform of FIG. 3C, the support rods 8A and 8B have some vibrations, but the residual vibrations as shown in FIG. 2B have been removed. Therefore, it goes without saying that the positions of the magnetic heads 8A and 8B attached to the support rods 8A and 8B are similarly controlled.

In the above-described embodiment, the case where the piezo actuators 6A and 6B suppress the vibration in the moving direction of the carriage mechanism 9 has been described. However, when the moving direction is the X direction, the Y direction and / or A piezo actuator may also be provided in the Z direction to suppress two-dimensional or three-dimensional vibration.

[0020]

According to the magnetic media inspection apparatus of the present invention, the amplitude of residual vibration after positioning is suppressed, and the time required for settling is reduced, thereby shortening the positioning time, that is, reducing the inspection time. There is an effect that the time can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration according to an embodiment of a magnetic media inspection apparatus of the present invention.

FIG. 2 shows a second example of the interference phase detection method of the optical interferometer of the present invention.
It is a figure showing the schematic structure concerning the embodiment.

FIG. 3 shows a third example of the interference phase detection method of the optical interferometer of the present invention.
It is a figure showing the schematic structure concerning the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disk rotation mechanism, 2 ... Magnetic disk, 3A, 3B
... Magnetic head, 4A, 4B ... Support arm, 5A, 5B ...
L-shaped slide guide, 6A, 6B: piezo actuator, 7A, 7B: L-shaped fixing member, 8A, 8B: support rod, 9: carriage mechanism, 10: acceleration sensor, 11 ...
MPU, 12 memory, 13 printer, 14 write control circuit, 15 read control circuit, 16 motor control circuit, 17 motor drive circuit, 18 applied voltage control circuit, 19 applied voltage generation circuit, 1A filter

Continued on the front page (72) Inventor Fujio Yamazaki 3-16-3 Higashi, Shibuya-ku, Tokyo Hitachi Electronics Engineering Co., Ltd.

Claims (4)

[Claims] A magnetic head for writing and reading data to and from a magnetic medium; a support arm means for supporting the magnetic head; a support arm means for holding the support arm means; A magnetic medium inspection apparatus comprising: a carriage means for positioning; and an actuator means for vibrating the support arm means in a direction to cancel the vibration of the magnetic head which vibrates according to the positioning operation of the carriage means. Magnetic media inspection device. 2. The apparatus according to claim 1, further comprising: an acceleration sensor for detecting an acceleration of the carriage when the carriage moves, and control means for setting a vibration of the actuator according to an acceleration signal from the acceleration sensor. Item 2. A magnetic media inspection device according to item 1. 3. The magnetic media inspection apparatus according to claim 1, wherein the actuator is a piezo-type actuator, and a bias in an extension direction is applied to the actuator in advance. 4. The magnetic media inspection apparatus according to claim 1, wherein a filter means for removing a high-frequency noise component from the acceleration signal is provided between the acceleration sensor and the control means.